Feed timing adjustment for sheet feeder

ABSTRACT

A method for feeding media items seriatim along a path of travel includes initiating a feed of a first media item along the path of travel and detecting the presence of the first media item along the path of travel. The time value is determined between initiating the feeding of the first media item and detecting the presence of the first media item. The initiating of feed of a second media item along the path of travel is controlled based on the determined time value between initiating the feeding of the first media item and detecting the presence of the first media item.

FIELD OF THE INVENTION

The present invention relates to a system and method for sheet feedingand, more particularly, to a system and method for sheet feeding thatadjusts the feed timing based on information related to downstream sheetacquisition data.

BACKGROUND OF THE INVENTION

Various feeding systems have been developed for media items, such assheets of paper or envelopes, for example. Such systems may haveapplications in inserter systems, sorters, mailing machines, and otherdevices. Various applications require a particular spacing, i.e., gap,between the various media items being fed, such that a system'sprocessing rate is maintained and downstream functions can be performedproperly in relation to each media item being transported along a pathof travel. Typically the media items are fed from a stack of media itemsonto a transport system for transport along the path of travel.

Conventional feeding systems are subject to factors that can causevariation of the feeding process and, thus, variation of the spacingbetween sequentially fed media items. These factors may relate to theoperation of the feeders, such as wearing and/or degradation of parts.Other factors relate to the media item being fed, such as variation inthe thickness of the item. Still other factors relate to environmentalaspects, such as humidity, that can result in changes to the media ordirt and dust that can result in changes in the operation of the feeder.Some of these factors may occur over a short or long period of time,from job run to job run of the equipment, and/or other within a singlejob run of the equipment.

For example, in vacuum feeding systems feeding sheets of paper, factorsthat may cause variations in the feeding process can include the time ittakes to open the valve to commence the vacuum build up, the time forthe vacuum to build up to dimple the paper, slippage through the drivedrum driving the paper forward, differences in the home position of thevarious servo motors, the stiffness of the paper, the position of thestripper bar, the roughness of the paper surface, the attachment of thepaper to the feeder drum, the presence of paper dust or other materialsthat may adhere to moving components, humidity, water content of thepaper, thickness of the paper, and orientation of the grain of thepaper.

Similarly, drive roller feeding systems can also have a variation in thefeeding process due to a range of factors, including many of those notedabove. Other factors include changes in friction between the driveroller and the media being fed from the feeder and the friction providedby the retard stone or retard roller, as well as changes in the relativeposition of the drive roller and the retard stone or roller. The factorsmay cause variations in the feeding process depending on the type andimplementation of the specific feeding system.

Variation in spacing of media items being fed seriatim from a feedersystem can create problems in system productivity and in media itemjams. If the spacing becomes too close between media items, jams mayoccur. For example, if a second media item is presented to a printingstation early because of a smaller than desired gap between media items,a jam may occur with the preceding media item still at the printingstation.

If the spacing becomes too large between media items, there may be adecrease in a system's productivity. For example, if a second media itemis presented to a printing station late because of a larger than desiredgap between media items, the printing station may be idle while waitingfor the arrival of the media item. Both of these types of problems arenot unique to printing stations, but relate to other types of stationsthat may be involved in the overall system. In some cases, the time toclear jams, a lower than desired feed rate, and idle time of the mediaitem processing stations, such as printing, folding, collating,inserting, and envelope flapping stations, can negatively impact asystem's productivity.

SUMMARY OF THE INVENTION

In the following description, certain aspects and embodiments of thepresent invention will become evident. It should be understood that theinvention, in its broadest sense, could be practiced without having oneor more features of these aspects and embodiments. It should also beunderstood that these aspects and embodiments are merely exemplary.

In some aspects of the invention, determining the time betweeninitiating a feed cycle and when a media item is detected as beingpresent at a particular point in the feeding system, such as a point inthe feed path, may be employed to adjust the feeding process to helpmaintain a desired spacing, i.e., gap, between various media items beingfed.

According to other aspects, the feeding process may be controlled foreach media item being fed and, if necessary, adjusted to help maintainthe desired spacing between successively fed media items by employinginformation as to the time between initiating a feed cycle for apreceding media item and when the preceding media item was detected asbeing present at a particular point in the feeding system.

In one embodiment, a method for feeding media items seriatim along apath of travel includes initiating a feed of a first media item alongthe path of travel and detecting the presence of the first media itemalong the path of travel. The time value is determined betweeninitiating the feed of the first media item and detecting the presenceof the first media item. The initiating of feed of a second media itemalong the path of travel is controlled based on the determined timevalue between the initiating the feeding of the first media item and thedetecting the presence of the first media item.

In another embodiment, a system for feeding media items seriatim along apath of travel includes a media item transport and a support structureadapted to support a stack of media items to be fed seriatim from thesupport structure onto the media item transport. A media item feeder isoperably connected to the support structure and to the media itemtransport. The media item feeder includes a mechanism which, wheninitiated to operate, is adapted to feed single media items from a stackof media items in the support structure onto the media item transport.

A detector is positioned in relation to the media item transport todetect the presence of a media item at a point on the media itemtransport. A controller is connected to the detector and to the mediaitem feeder. The controller is operable to initiate the media itemfeeder to feed a single media item from a stack of media items in thesupport structure onto the media item transport based on a determinedtime value from the initiation of a feed onto the media item transportof an preceding media item, and on information from the detectorrelating to detection of the preceding media item in relation to anexpected time value, whereby spacing on the media item transport betweenmedia items fed seriatim onto the media item transport is controlled.

Aside from the structural and procedural arrangements set forth above,the invention could include a number of other arrangements, such asthose explained hereinafter. It is to be understood that both theforegoing description and the following description are exemplary only.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments of theinvention, and together with the general description given above and thedetailed description of the preferred embodiments given below, serve toexplain the principles of the invention. As shown throughout thedrawings, like reference numerals designate like or corresponding parts.

FIG. 1 is a schematic view of a feeder system incorporating anembodiment of the present invention;

FIG. 2 is a schematic view of the feeder system of FIG. 1 illustratingone mode of operation;

FIG. 3 is a schematic view of the feeder system of FIG. 1 illustratinganother mode of operation;

FIG. 4 is a schematic view of the feeder system of FIG. 1 illustratingyet another mode of operation;

FIG. 5 is a schematic view of the feeder system of FIG. 1 illustrating afurther mode of operation; and

FIG. 6 is a flow chart illustrating an embodiment of the methodaccording to the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference is now made to FIG. 1. A vacuum feeder system shown generallyat 10 includes a series of media items 12 stacked in a support structure13 for feeding onto a transport path 14. The media items 12 may besheets of paper, envelopes, or other media, for example, that issuitable for being fed in series along a path of travel. A feed drum 16adapted to be driven by a feed motor 18 is positioned below the stack ofmedia items 12. The feed drum 16 has a series of apertures in theperiphery such that when a valve 20 is caused to open, a vacuum source22 creates a vacuum in the drum, causing the lead edge of the lowestmedia item in the stack of media items 12 to be pulled onto the feeddrum below a stripper blade 24 and into the transport path 14.

The operation of the valve 20, as well as the feed motor 18 and atransport motor 26, are controlled by a controller 28 that providescontrol and program store for the feeder system 10. The system furtherincludes a detector system 30, such as an optical detector, which ispositioned along the transport path 14 to detect media items drivenalong the transport path 14. The media items, such as media item 36, aredriven by the feed motor 18 driving feed drum 16, along with thetransport motor 26 driving feed roller 32, which cooperates with idlerroller 34, to cause a media item to be fed out from the media stack 12and to be driven along the transport path 14.

Reference is now made to FIG. 2, which shows a first media item 36having been fed out from the stack of media items 12, being detected bythe detector system 30. The detection of the media item causes thecontroller 28 to turn off the valve 20. The valve 20 is turned offbefore the trail edge of the media item 36 is fully extracted from thestack, so as to prevent the valve from being opened and causing the feeddrum 16 to prematurely cause a feed of a further media item onto thetransport path 14.

Reference is now made to FIG. 3. In FIG. 3, the first media item 36 isshown as having progressed along the transport path 14 and a secondmedia item 38 is shown as having been withdrawn from the stack of mediaitems 12 and fed onto the transport path 14. A third media item 40, atthe bottom of the media item stack 12 immediately above the media item38, is positioned to be the next media item to be fed onto the transport14. The gap 41 is the appropriate desired gap between media items. Thesize of a desired gap depends on the specific equipment, processingstations for the media items, and the particular application.

Reference is now made to FIG. 4., where the first media item 36 and thesecond media item 38 are shown to have an improperly small spacing,indicated as the gap 42. This gap 42 is a smaller than desired gap. Thissituation can cause jams in the equipment as the media items move downthe transport path 14 and/or are fed into various stations forprocessing the media items such as printing, folding, collation,insertion, flapping envelopes, etc. Correction of this gap situation ismade by operation of the system of the invention in accordance with theflow chart shown in FIG. 6. This is accomplished by controlling thefeeder 10 in the initiation of the feed of the next media item 40.

Reference is made to FIG. 5. In a like manner to FIG. 4, the gap betweenthe media item 36 and media item 38 is improper. In this situation thegap 44 is too large. This can impact productivity of the system,reducing the number of media items fed onto the transport path 14.Various stations for processing the media items such as printing,folding, collation, insertion, flapping envelopes, etc., may have idletime while waiting for arrival of a media item and are operating belowthe operating speed desired. Again, correction of this gap situation ismade by operation of the system in accordance with the flow chart shownin FIG. 6. This is accomplished by controlling the feeder 10 in theinitiation of the feed of the next media item 40.

Reference is now made to FIG. 6. The operation of the feeder system 10in accordance with the flow chart employs the detection time, that is,the time from the initiation of the feed of a media item until the mediaitem is acquired as detected by the detector 30. This determined time isemployed in controlling the initiation of the feed of the next mediaitem. The gap between media items is controlled by timing the initiationof feed of the next item. The distance between adjacent media items(i.e., the gap) is not measured. The determined time is utilized inrelation to an expected time for detection of acquisition of the mediaitem to make any adjustments in initiating the feed of the next mediaitem in the stack of media items 12. Adjustments can be made to avoid asituation where gap positioning between various media items becomes aproblem. The system enables adjustments to be made to avoid jamming andother problems associated with improper gap between media items.

The program shown in FIG. 6 is stored in the program store of thecontroller 28, which provides control and program store for the feedersystem 10. The process starts at 50. A decision is made whether a feedrequest has occurred at decision box 52. If no feed request has beenmade the system loops back. Where a feed request has been made at block54, the controller 28 causes the valve 20 to be opened. At decision boxblock 56 a determination is made if the media item has arrived, that is,whether the media item has been detected by the detector system 42. Ifthe media item has not arrived the system loops back and waits until itis determined that the media item has arrived.

When the media item has arrived, at block 58, the valve 20 is closed. Atblock 60, the actual acquire time, that is, the time from initiation ofthe feeding of the media item until the media item is detected is eithermeasured or calculated, as will be explained below. This determined timeis the actual time to acquire the media item at a point in the system,such as a point on the transport path from the time of the initiation ofthe media item feed, which is measured and/or calculated by employingdistance and velocity. For example, the rotational distance moved andvelocity of movement of the feed drum motor 18 or the rotationaldistance moved and velocity of movement of the transport motor 26 can beutilized to calculate the acquire time from feed initiation untildetection.

The determined time and the expected time can be measured or calculated.This is carried out by measuring time, distance, or a combination ofboth time and distance, and employing appropriate calculations. Theterms “determining time value,” “determined time value,” “determiningexpected time value,” and “expected time value,” as used herein, areeach intended to include and cover measuring time and/or distance andmaking any calculations to establish the value. The term “expectedvalue” also further includes and covers a predetermined expected timethat may be employed in the operation of the feeder system.

A determination is then made at decision box 62 if the acquired time isearly by comparing it against the expected time. If the acquired time isnot early, a determination is then made at decision block 64 if theacquired time is late by comparing it against the expected time. If theacquired time is not late, the system loops back and a determination ismade at decision block 66 if the minimum time to the next feed has beencompleted. The expected time can be a predetermined value or one that iscalculated based on known factors that affect the expected time, such asthe velocity of the feed or transport motor or the travel distance ofthe motor after feed. If the minimum time to the next feed of a mediaitem has been completed, the system continues to decision block 52. Ifthis is not the case the system loops back.

As discussed above, the expected time can be a predetermined time value.The expected time can also be represented by the movement of a part fromone point to another point. The expected time is thus essentiallycalculated by known factors of velocity (e.g., inches per second) anddistance (e.g., inches). Examples of moving parts that may be used forrepresenting the expected time are (1) the velocity of a moving part ofthe feed motor or a part driven by the feed motor and the distance movedby such moving part or (2) the velocity of a moving part of thetransport motor or a part driven by the transport motor and the distancemoved by such moving part.

Returning to decision block 62, where the media item has been acquiredearly, the minimum time to the next feed is increased at block 68 andthe system continues to decision block 66. Where the media item has beenacquired late as determined by decision block 64, the minimum time tothe next feed is reduced at block 70 and the system continues todecision block 66. The determination at decision blocks 62 and 66 is inrelation to an expected time. For example, the expected time representsthe time it is expected that a media item will arrive at the detector 30after the initiation of a feed cycle. The measured or calculated acquiretime, a determined time for the specific media item, is compared to theexpected time that the media item should have arrived at the detector 30after initiation of the feed cycle.

It should be noted that the increase of minimum time to the next feedand the reduction of minimum time to the next feed, block 68 and block70, are not necessarily of the same increment of time. The increaseincrement in feed time may be smaller than the decrease increment infeed time. This is to avoid the possibility of a jam. Thus, if the gapis too small, immediate action may be desirable to increase the gap toavoid a jam by significantly increasing the time to the initiation offeed of the next media item. If the gap is too large, gradual reductionsin the gap size may be made to more gradually change the initiation ofthe next feed and increase the productivity of the system until thedesired gap size is achieved. Where the acquire time is not too earlyand not too late, as determined by the decision blocks 62 and 64, thereis no adjustment in the minimum time to the next feed. The adjustment infeed initiation timing between media items in that case is zero.

By keeping track of the acquire times, the feeding system 10 can be madeto function more as intended with the desired high rate of speed offeeding media items, while avoiding undesired variations in media itemgaps that could slow the process or create jams, which reduce theproductivity of the system.

The system, when needed, increases or decreases the time beforeinitiating the feed of a media item when the determined time differsfrom the expected time of the preceding media item. The adjustment(increases or decreases) or non-adjustment of the time is based on theimmediately preceding media item feed cycle. That is, the time betweeninitiating the feeding of the media item staged to be fed is controlledto be increased or decreased compared to the time lapse between the feedinitiation of the immediately preceding media item and the media itembefore the immediately preceding media item. Thus, the feed initiationis controlled on the fly for every media item being fed seriatim fromthe stack of media items. When, however, the determined time is withinthe limits for the expected time, no timing adjustment change is madewhen controlling the time before initiating the feed of a media item inrelation to the immediately preceding feed cycle. The limits for theexpected time may vary for the particular system involved.

By controlling the time before initiating the feed of a media item inrelation to the immediately preceding feed cycle, an adjustment can bemade in initiating the feed of this media item only when needed and thenin real time. Adjustment is only made in initiating the feed of a mediaitem when the determined feed time of the media item of an immediatelypreceding feed cycle is detected as being out of limits, that is, thedetermined feed time of the media item of an immediately preceding feedcycle is detected as being early or late. When the determined feed timeof a media item of an immediately preceding feed cycle is detected asbeing within the limits of the expected time, no adjustment is made inthe initiation of the feeding of the media item to be next fed onto thetransport. This enables the gap between media items being fed onto thetransport to be maintained and adjusted, media item by media item. Thus,gap control between media items is maintained even as parts wear overtime or other factors occur that impact feeding during a particular jobrun. This helps maintain the productivity of the feeding system byhelping to reduce media item jams while maintaining the desired mediaitem feed rate.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure andmethodology described herein. Thus, it should be understood that theinvention is not limited to the examples discussed in the specification.Rather, the present invention is intended to cover modifications andvariations.

1. A method for feeding media items seriatim along a path of travel,comprising: initiating a feed of a first media item along the path oftravel; detecting the presence of the first media item along the path oftravel; determining the time value between initiating the feed of thefirst media item and detecting the presence of the first media item; andcontrolling initiating a feed of a second media item along the path oftravel based on the determined time value between initiating the feed ofthe first media item and detecting the presence of the first media item.2. The method of claim 1, wherein controlling initiating the feed of thesecond media item along the path of travel is based on the determinedtime value in relation to an expected time value.
 3. The method of claim2, wherein controlling initiating the feed of the second media itemalong the path of travel increases the time before initiating the feedof the second media item in relation to an immediately preceding feedcycle when the determined time value is less than the expected timevalue.
 4. The method of claim 2, wherein controlling initiating the feedof the second media item along the path of travel decreases the timebefore initiating the feed of the second media item in relation to animmediately preceding feed cycle when the determined time value isgreater than the expected time value.
 5. The method of claim 2, whereincontrolling initiating the feed of the second media item along the pathof travel does not change the time before initiating the feed of thesecond media item in relation to an immediately preceding feed cyclewhen the determined time value is within defined limits of the expectedtime value.
 6. The method of claim 2, wherein controlling initiating thefeed of the second media item along the path of travel increases thetime before initiating the feed of the second media item in relation toan immediately preceding feed cycle when the determined time is lessthan the expected time value and wherein the controlling the initiatingthe feed of the second media item along the path of travel decreases thetime before initiating the feed of the second media item in relation tothe immediately preceding feed cycle when the determined time value isgreater than the expected time value.
 7. The method of claim 3, whereinthe increase of the time before initiating the feed of the second mediaitem is an increase increment of time.
 8. The method of claim 4, whereinthe decrease of the time before initiating the feed of the second mediaitem is a decrease increment of time.
 9. The method of claim 2, whereincontrolling initiating the feed of the second media item along the pathof travel increases the time in an increase increment of time beforeinitiating the feed of the second media item in relation to a precedingfeed cycle when the determined time value is less than the expected timevalue, controlling initiating the feed of the second media item alongthe path of travel decreases the time in a decrease increment of timebefore initiating the feed of the second media item in relation to animmediately preceding feed cycle when the determined time value isgreater than the expected time value, and controlling initiating thefeed of the second media item along the path of travel does not changethe time before initiating the feed of the second media item in relationto a preceding feed cycle when the determined time value is withindefined limits of the expected time value.
 10. The method of claim 9,wherein the increase increment of time and the decrease increment oftime are different time increments.
 11. The method of claim 9, whereinthe first media item and the second media item are sheets of paper beingfed from a stack of sheets of paper.
 12. The method of claim 9, whereinthe first media item and the second media items are envelopes being fedfrom a stack of envelopes.
 13. The method of claim 10, wherein theincrease increment of time is a larger time increment than the decreaseincrement of time.
 14. The method of claim 10, wherein the media itemfeeder is a vacuum type feeder.
 15. The method of claim 10, wherein themedia item feeder is a drive roller type feeder.
 16. A system forfeeding media items seriatim along a path of travel comprising: a mediaitem transport; a support structure adapted to support a stack of mediaitems to be fed seriatim from the support structure onto the media itemtransport; a media item feeder operably connected to the supportstructure and to the media item transport, the media item feederincluding a mechanism that, when initiated to operate, is adapted tofeed single media items from a stack of media items in the supportstructure onto the media item transport; a detector positioned inrelation to the media item transport to detect the presence of a mediaitem at a point on the media item transport; and a controller connectedto the detector and to the media item feeder, the controller operable toinitiate the media item feeder to feed a single media item from a stackof media items in the support structure onto the media item transportbased on a determined time value from the initiation of a feed onto themedia item transport of an immediately preceding media item and oninformation from the detector relating to detection of the precedingmedia item in relation to an expected time value, whereby spacing on themedia item transport between media items fed seriatim onto the mediaitem transport is controlled.
 17. The system of claim 16, wherein thecontroller is operable to increase the time before initiating feeding ofa media item in relation to an immediately preceding feed cycle when thedetermined time value is less than the expected time value, thecontroller is operable decrease the time before initiating feeding ofthe next media item in relation to an immediately preceding feed cyclewhen the determined time value is greater than the expected time valueand the controller is operable to initiate feeding of the next mediaitem with no change in time in relation to an immediately preceding feedcycle when the determined time value is within defined limits of theexpected time value.